Method and device for the use of high temperature heat energy in particular of nuclear origin

ABSTRACT

THE INVENTION RELATES TO THE RECOVERING OF THE HIGHTEMPERATURE HEAT-ENERGY DISSIPATED IN THE CORE OF A NUCLEAR REACTOR AND USING A TIN CYCLE IN WHICH STANNIC OXIDE (SNO2) IS DECOMPOSED AT HIGH TEMPERATURE INTO A GASEOUS MIXTURE OF STANNOUS OXIDE (SNO) AND OXYGEN (O2) WHICH, AFTER COOLING, GIVES SOLID STANNOUS OXIDE (SNO) AND OXYGEN. THEN STANNOUS OXIDE IS ALLOWED TO DISMUTE INTO STANNIC OXIDE (SNO2) WHICH IS RECYCLED AND INTO TIN WHICH IS USED TO DECOMPOSE WATER STEAM (H2O) INTO (H2) AND INTO AMINE OXIDE (SNO2) WHICH IS RECYCLED.

Sept. 25, 1973 s um U METHOD AND nmvlm-z v01: THF Usm orHlUll-IEMPBRAI'URL HEAT-ENERGY, IN PARTICULAR OF NUCLEAR ORIGIN FiledMay 18, 1972 2 Sheets-Sheet 1 D. SOURIIAU Sept. 25, 1973 METHOD ANDDEVICE FOR THE USE OF HIGH-TEMPERATURE HEAT-ENERGY, IN PARTICULAR OFNUCLEAR ORIGIN Filed May 18, 1972 2 Sheets-Sheet 2 C Om W A 3 0 0mmLswao United States Patent i 3,761,352 METHOD AND DEVICE FOR THE USE OFHIGH- TEMPERATURE HEAT-ENERGY, IN PARTICU- LAR OF NUCLEAR ORIGIN DanielSouriau, Paris, France, assignor to Gaz de France, Paris, France FiledMay 18, 1972, Ser. No. 254,755 Int. Cl. G21d 9/00 US. Cl. 176-57 11Claims ABSTRACT OF THE DISCLOSURE The invention relates to therecovering of the hightemperature heat-energy dissipated in the core ofa nuclear reactor and using a tin cycle in which stannic oxide (Sn0 isdecomposed at high temperature into a gaseous mixture of stannous oxide(SnO) and oxygen (0 which, after cooling, gives solid stannous oxide(SnO) and oxygen. Then stannous oxide is allowed to dismute into stannicoxide (SnO' which is recycled and into tin which is used to decomposewater steam (H O) into (H and into amine oxide (SnO which is recycled.

The present invention has essentially for its object a method and adevice enabling the high-temperature heatenergy dissipated. forinstance, in a nuclear reactor, to be used through recovery andconversion.

In most of the plants worked or designed at the present time, thehigh-temperature heat-energy produced in the core of a nuclear reactoris extracted by means of an exchange fluid such as for instance water,helium or sodium. The exchange fluid sometimes works directly inturbines. More often, it constitutes the hot source of a conventionalthermodynamic cycle using, in particular, turbines and water boilers.

The efficiency of such cycles is not very high and, moreover, investmentexpenditure for the plants, in particular for the turbine-boiler unit,heavily burdens the cost of every kilowatt-hour produced.

The invention is directed at reducing the cost of the recoverable energyand at producing simultaneously interesting and valuable chemical bodiessuch as hydrogen and oxygen.

The method of the invention is characterized notably in that it consistsin using the high-temperature heat-energy released in the reactor tomelt stannic oxide (SnO e.g. at about 1700 C., in letting the latterdecompose into a gaseous mixture of stannous oxide (SnO) and oxygen (0in cooling or chilling the said mixture, e.g. at about 700 C., inseparating the solid stannous oxide from the oxygen, in performing adismutation and separation of the solid stannous oxide into solidstannic oxide and liquid tin, e.g. at about 700 C., in recycling thestannic oxide, making the tin react with steam so as to form stannicoxide, which is recycled, and hydrogen (H which is separated, and inrecovering the hydrogen and oxygen produced.

Thus, as a result of a complex cycle of oxydation-reduction of tin, thesteam is dissociated into hydrogen and oxygen.

As appears from the investigations performed, the economic advantages ofthe invention are considerable. This results in particular from the factthat the aforementioned cycle enables the high-potential calories in thecore of the reactor to be used to the best. Furthermore, the productionof large amounts of hydrogen and oxygen is economically highlyinteresting and capable of finding a great number of openings.

The invention also relates to a plant for the carrying out of the methodof the invention, the said plant being remarkable notably in that itcomprises at least one Patented Sept. 25, 1973 stannic-oxide meltingchamber, the heat source of which is constituted by pipes through whichliquid tin heated to a high temperature, e.g. about 1800 C., is made toflow in contact with a heat source such as a nuclear reactor, a coolingor chilling device such as water and steam exchangers placed in the pathof the gaseous mixture of stannous oxide and oxygen resulting from thedecomposition of the stannic oxide, a device for separating the oxygenfrom the solid stannous oxide, a device for separating the solidstannous oxide from the liquid tin produced by the dismutation of thestannous oxide, a reaction column for the decomposition of the steam bythe tin, resulting in the formation of hydrogen and stannic oxide, andmeans for the recycling of the stannic oxide. The techniques used insuch a plant are simple as compared with those used in an elaborateconventional cycle employing high-, mediumand low-pressure turbines,boilers with economizers, superheating and resuperheating, multipleexchangers, etc., some of these devices being operated at very hightemperatures and pressures.

The invention will appear more clearly from the following descriptionmade with reference to the appended drawings illustrating, solely by wayof example, one form of embodiment of the invention.

In the said drawings:

FIG. 1 is a diagrammatic view illustrating the method of the inventionas a whole;

FIG. 2 is a more detailed and precise view of the equipment used for thecarrying out of the tin oxydationreduction cycle according to theinvention;

FIG. 3 is a detailed view illustrating more specifically one of thedevices shown in FIG. 2.

Reference is first made to FIG. 1 illustrating diagrammatically themethod of the invention as applied to the use of the heat released inthe core of a nuclear reactor to achieve the dissociation of water byusing a tin oxydation-reduction cycle, and to simultaneously producesteam for driving an alternator.

The heat is extracted from the core of the reactor by means of a coolingcircuit through which liquid tin is made to flow. The liquid tin flowingout from the nuclear reactor at 1820 C., enters, at 10, an exchanger forthe heating of a stannic-oxide (SnO melting chamber 11. The tin leavingthe exchanger at 12 is conveyed back into the reactor at, for instance,1750 C.

The stannic-oxide melting chamber 11 receives the stannic oxide from thewater-dissociation column 13 and from the stannous-oxide (SnO)dismutation bunker 14.

The liquid stannic oxide heated in the melting chamber 11 to about 1700"C. decomposes spontaneously according to the endothermic reaction:

The oxygen and gaseous stannous oxide heated to 1700 C. flow through theconduit 15. The gaseous mixture is cooled or chilled, for instance downto about 700 C., by entering into contact with an exchanger 16 fed withWater at 17 and supplying steam at 18. Under this cooling action, thestannous oxide becomes solid and is separated from the oxygen, which isextracted from the plant at 19. The stannous oxide is deposited at 20 onthe bottom of a bin 21, from which it is admtited into the bunker 14.

In the bunker 14, advantageously at about 700 0., occurs the dismutationof the tin according to the reaction:

The reaction is slightly exothermic, whereby the heat losses through thewalls are substantially compensated for. At that temperature, thestannic oxide is solid whereas the tin is liquid. The separation of thetin from the stannic oxide is obtained simply by letting the stannicoxide roll and slide on an inclined grid 22. The liquid tin is collectedin the lower portion 23 of the bin 14, whereas the stannic oxide isseparated in the upper portion 24 of the bin and returns to the meltingchamber 11.

The liquid tin extracted from the bin 14 is conveyed by a pump 25 intothe upper portion of the water dissociation column 13 where it isatomized by an atomizer 26.

A counter-current flow of steam proceeding from the exchangers 16. isconveyed into the lower portion of the column 13 at 27.

In the column 13 occurs the reduction of the water according to thereaction:

This reaction is slightly exothermic. The steam is supplied for instanceat 250 C. and the tin at about 400 C. At the reaction temperatureconsidered, the stannic oxide produced is solid and is collected at thebottom of the column in a bin 28 from which it is conveyed back into themelting chamber 11. The hydrogen produced is collected at 29.Advantageously, the steam introduced into the column 13 may be underpressure, so that the hydrogen produced is collected under pressurewithout the reduction reaction being substantially modified.

The steam produced in the exchanger 16 and unused during the process istaken out at 13 and may be used to supply a thermal power station of aconventional type.

It is thus obvious that, in the method just described, the dissociationof water into its components, namely oxygen and hydrogen, is performedby deriving the necessary heat from the core of the reactor. The reactoris thermodynamically interesting, for the high-temperature calories areused directly at their potential in the cycle. Moreover, the techniquesrequired for the carrying out of the cycle give rise to no particulardifficulties. In addition, any casual leakage of the heat-exchange fluid(tin) can by no means be detrimental to the process, since no foreigndangerous matter is introduced into the cycle.

Reference is now made to FIGS. 2 and 3 illustrating more specificallyone form of embodiment of a plant according to the invention.

In FIG. 2, the nuclear reactor is shown at 31. The heat produced thereinis withdrawn through a cooling circuit through which tin is conveyed.The tin 1820 C. leaves the reactor at 32 and is returned into the latterat 33 at a temperature of 1750" C. after exchanging heat with the plant.

At 34 is shown the main stannic-oxide melting chamber, which is annularin shape. In the latter are mounted heat-exchange pipes of the type usedin Field boilers, or of the glove-finger type 35, which are lickedexternally by the liquid tin supplied through the conduit 32. Afterpassing externally through the layers of pipes 35, the exchange fluid isconveyed back into the return conduit 33. An auxiliary stannic-oxidemelting chamber 36, the function of which will be explained later, isalso heated by Field pipes 37, also supplied through the circuit 32, 33.

The stannic oxide (SnO melted in the chamber 34 at about 1700 C.decomposes, as already mentioned, into a gaseous mixture of stannousoxide and oxygen, which is collected and channeled in a central space ofthe plant, forming an annular chamber 38. This gaseous mixture is cooledor chilled by entering into contact with water or steam heat-exchangers39 arranged annularly at the outlet of the chamber 38.

As a result of this cooling, the temperature of the product falls toabout 700 C. in the external annular portion 40. The gaseous oxygen andthe solid stannous oxide (SnO) are separated in cyclones 41. The oxygenis released in the upper portion of the plant at 42 after beingcollected in the annular conduit 43 closing the space 40.

The solid stannous oxide separated in the cyclones 41 is subjected todismutation, i.e. is decomposed into solid stannic oxide and liquid tinat about 700 C. in the annular column 44. As appears more clearly fromFIG. 3, the cyclones 41 let the solid stannous oxide flow on helicalgrids 45, under which the liquid tin is collected in gutters 46, whereasthe stannic oxide is collected at the bottom of the grids 45 where itfalls onto the bottom 47 of the column 44. There, the stannic oxide isliquified by a current of stannic oxide circulating as a result ofoverflow as shown by the arrows and proceeding from the melting chamber34.

The whole of the equipment just described is located in a sealinglyclosed concrete enclosure 48.

The liquid tin collected at the bottom of the column 44 is conveyedthrough a circuit 50 and by means of a pump 51 to the top of a column 52where it is atomized as shown diagrammatically at 53.

-A counter-current flow of steam, e.g. at 250 0., produced by theexchangers 39 is conveyed into the bottom of the column 52 at 54.

In this column, which may be for instance under atmospheric pressure,the steam is reduced into hydrogen which is released at the top of thecolumn, whereas the tin is oxidized into solid stannic oxide at thattemperature and is deposited at the bottom of the column in a bin '55.This reduction may also be performed under pressure.

Therefrom, the stannic oxide falls into an auxiliary melting chamber 56wherein the melting is performed through the medium of the meltingchamber 36 and by means of overflow circulation between the two meltingchambers 56 and 36, as illustrated by the arrows. The liquid stannicoxide is recycled, through the medium of a cyclone 57, at the bottom ofthe column 44.

A few orders of magnitude characterizing a plant of the type illustratedin FIGS. 2 and 3 are given hereinunder.

Thermal power of the nuclear reactor, mw. 840 Rate-of-flow of theheat-exchange fluid (Sn),

mP/s. 8 Rate-of-flow of the stannous oxide and the oxy gen in chamber38, m. /s. 1500 Rate-of-flow of the solid stannous oxide at the cyclone,kg./s. Oxygen output, NmF/h. 50,000 Rate-of-fiow of the steam admittedinto the column 53, t./h. 90 Hydrogen output from the column 52,

Nm. /h. 100,000 Rate-of-flow of liquid tin at the column 52,

l./s. 11 Diameter of enclosure 48, m. 20 Height of enclosure 48, m. 16Absolute pressure within enclosure 48, b. 0.2 Diameter of column 52, m.4 Height of column 52, m. 25 Pressure in column 52, b. 1 Electric powerof the alternator driven by the heat-power station supplied with steamby the exchangers 39, mw.

Therefore, by means of such a plant and using a reactor whose thermalpower is 840' mw., there is obtained, without using highly elaboratetechniques, an electric power of 180 mw. and, simultaneously, 100,000normal In. of hydrogen per hour and 50,000 normal In. of oxygen perhour.

From the foregoing it appears that the method according to the inventionis highly advantageous from the economic and technical points of viewand is an eflicient solution for the recovery of high-potential thermalenergy.

Of course, the invention is by no means limited to the form ofembodiment described and illustrated, which has been given by way ofexample only. In particular, it comprises all the means constitutingtechnical equivalents to the means described as well as theircombinations, should the latter be carried out according to the spiritof the invention.

What is claimed is:

1. Method of recovery and conversion of high-temperature heat-energydissipated in a nuclear reactor comprising the steps of using thehigh-temperature heatenergy released in the reactor to melt stannicoxide at about 1700 C., letting the latter decompose into a gaseousmixture of stannous oxide (SnO) and oxygen (02), in cooling or chillingthe said mixture, separating the solid stannous oxide from the oxygen,performing a dismutation and separation of the solid stannous oxide intosolid stannic oxide and liquid tin, recycling the stannic oxide, makingthe tin react with steam so as to form stannic oxide, which is recycled,and hydrogen (H which is separated, and recovering the hydrogen andoxygen produced.

2. Method according to claim 1, wherein the high-temperatureheat-exchange fluid used is liquid tin which cools the heat source.

3. Method according to claim 1, wherein said cooling of gaseous mixtureof stannous oxide (SnO) and oxygen is performed at about 700 C.

4. Method according to claim ll, wherein said dismutation and separationof stannic oxide and liquid tin is performed at about 700 C.

5. Method according to claim 3, wherein use is made, in order to chillthe reaction of decomposition of the stannic oxide into stannous oxideand oxygen, of a water and steam heat-exchanger.

6. Method according to claim 1, wherein the various stages of the tincycle are carried out under substantially atmospheric pressure or undera lower pressure.

7. Method according to claim 6, wherein the reduction of the steam bythe tin is carried out under a pressure higher than atmospheric.

8. Plant for the recovery and conversion of high-temperature heat-energydissipated in a nuclear reactor comprising at least one stannic-oxide(SnO melting chamber, pipes through which is made to flow liquid tinheated to a temperature of about 1800 C. in contact 'with the hot sourceof said nuclear reactor, said pipes passing through said stannic-oxidemelting chamber and forming its heat source, a space in which escapesthe gaeous mixture of stannous oxide (SnO) and oxygen (0 resulting fromthe decomposition of stannic oxide (SnO a cooling or chilling devicesuch as Water and steam exchangers placed in said space in the path ofsaid gaseous mixture of stannous oxide and oxygen, a device forseparating the oxygen from the solid stannous oxide resulting from saidchilling of said gaseous mixture, a device for separating the solidstannic oxide from the liquid tin resulting from the spontaneousdismutation of the stannous oxide, a reaction column for thedecomposition of the steam by the tin, resulting in the formation ofhydrogen and stannic oxide, stannic-oxide recycling means, and means forfeeding said column with steam and with the tin resulting from saiddismutation of said stannous oxide.

'Plant according to claim 8, wherein the devices for separating theoxygen and the stannous oxide comprise devices of the cyclone type.

lltl. Plant according to claim 8, wherein the devices for separating thestannous oxide and the tin are constituted by a grid-type separatorcomprising inclined grids on which the solid stannic oxide rolls andinclined surfaces or gutters on which flows the liquid tin dippingthrough the said grids.

11. Plant according to claim 8, wherein the column for the decompositionof the steam by the tin ends at its base with a gutter and receives thesolid stannic oxide produced by the reaction, and the said gutter opensinto a space into which is conveyed a flow of liquid stannic oxideheated by the said heat-exchange pipes through which flows the saidliquid tin.

References Cited UNITED STATES PATENTS 3,535,082 10/1970 Nurnberg et al423-657 3,155,547 11/1964 Siebker 17639 FOREIGN PATENTS 1,109,652 4/1968Great Britain 176-39 HARVEY E. BEHREND, Primary Examiner US. Cl. X.R.

